Earlier this month, Microsoft added an update to its malicious software removal tool (MSRT) that specifically targets Koobface. The virus shows up in fake messages from "friends" that encourage users to click on a malicious link that can steal user ID and password information, and be used to spread the virus.

"By adding this threat to the more than 100 threat families already in MSRT, we're helping to protect hundreds of millions of people," Jeff Williams, principal group manager for the Microsoft Malware Protection Center, wrote in a blog post. "Since releasing our newest version of MSRT, we've removed Koobface nearly 200,000 times from over 133,677 computers in more than 140 different locales around the world."

Microsoft is also working to detect new variants of Koobface, Williams wrote.

"Koobface is constantly changing to avoid detection, or as we call it 'highly polymorphic,' with over 20,000 variations to date," he said. "Sometimes we remove the virus from the same computer more than once."

Consumers with Windows-based machines who use automatic updates should be receiving MSRT each month as part of a standard security update. If you're concerned that Koobface might already been on your computer, Microsoft offers a free online virus scanner on its site.

Chloe Albanesius has been with PCMag.com since April 2007, most recently as Executive Editor for News and Features. Prior to that, she worked for a year covering financial IT on Wall Street for Incisive Media. From 2002 to 2005, Chloe covered technology policy for The National Journal's Technology Daily in Washington, DC. She has held internships at NBC's Meet the Press, washingtonpost.com, the Tate Gallery press office in London, Roll Call, and Congressional Quarterly. She graduated with a bachelor's degree in journalism from American University...
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